1. Field Of The Invention
This invention relates to an analog operation circuit, and more particularly to an analog operation circuit comprising a multi-collector lateral transistor.
2. Description Of The Prior Art
Such circuits as one shown in FIG. 3 have been known as an analog operation circuit. The circuit of FIG. 3 comprises a first differential amplifier comprising transistors Q.sub.3 and Q.sub.4, a second differential amplifier comprising transistors Q.sub.5 and Q.sub.6, and a third differential amplifier having a transistor Q.sub.7 connected to the common emitter of the first differential amplifier and a transistor Q.sub.8 connected to the common emitter of the second differential amplifier. Each one input terminal (Q.sub.4 and Q.sub.5) of said first and second differential amplifiers is connected in common to one terminal of a first input signal V.sub.in1, and each other input terminal (Q.sub.3 and Q.sub.6) of said first and second differential amplifiers is connected in common to the other terminal of the first input signal V.sub.in1. A second input signal V.sub.in2 is applied commonly to the inputs of the third differential amplifier (Q.sub.7 and Q.sub.8). The total output (V.sub.out1 and V.sub.out2) is derived from the outputs of the first and second differential amplifiers.
The operation of this circuit can be described as follows.
The collector current I.sub.c7 of the transistor Q.sub.7 is varied by the input signal V.sub.in2. This current I.sub.c7 is further varied by the input signal V.sub.in1. The output voltage V.sub.out1 can be represented by the following formula. EQU V.sub.out1 = gm' .multidot. V.sub.in1 .multidot. V.sub.in2 .multidot. R.sub.4 ( 1)
where, gm' is the mutual conductance (transconductance) determined by the applied voltage and R.sub.4 is the collector resistance. Thus, the circuit has an operation function.
The above circuit structure, however, apparently has such problems as that the circuit is complicated and the number of elements is large.